428 Journal of Agricultural Research voi. xix, N0.9 



to be of a very much lower density than normal barley starch. They 

 did not stain readily and were indefinite in outline. Rapid infiltration 

 of starch began about the time that rapid growth of length ceased. By 

 the ninth day after flowering the starch grains were of very uniform 

 appearance. From this time the development was more irregular, not 

 all the grains continuing to increase in size. By the fourteenth day 

 small grains were apparent among the larger ones, as though new starch 

 grains were forming. These small grains are found in the cells from 

 this time until maturity. The fifteenth and sixteenth days represent a 

 period when the awns are likely to drop off. The dropping of the awns, 

 apparently, coincides with the completion of a stage of starch infiltra- 

 tion. From this time on, although the rate of starch deposit holds up 

 fairly well, the accumulation is made by the continued development of 

 only a part of the large grains and the packing of the interstices between 

 the larger grains with smaller ones, rather than a uniform development 

 of all grains as at first. 



The first starch was found in the older cells in the middle of the 

 flanks. It is probable that new cells are added about the periphera of 

 the endosperm and especially near the furrow for some time. It is 

 unlikely that new cells are added to the periphera after the fifteenth 

 day from flowering. The new cells added near the furrow develop in 

 a way entirely comparable to the first cells of the starch endosperm. 

 Such cells are shown in Plate 91. After the first two weeks the trans- 

 portation of food material to the sides remote from the furrow may 

 not be so readily accomplished. Here the cells last formed may remain 

 nearly free from starch at maturity, although the development of the 

 cell walls demonstrates that the cells are not young. 



SUMMARY 



This paper presents data showing the growth of the Hannchen 

 variety of barley from flowering to maturity, taken at 12-hour inter\-als. 

 In the early stages of development, measurable growth occurs during 

 12-hour intervals, and during 24-hour intervals until near maturity. 

 The period from flowering to maturity in three successive years at Aber- 

 deen has been 26 days. 



Measurements were taken of the length, lateral diameter, and dorso- 

 ventral diameter of the kernel. The growth immediately after flower- 

 ing is so rapid that the increase in length is readily measurable at 

 12-hour intervals. The length growth is completed by the seventh day, 

 and as soon as the rate of growth in length decreases the lateral diameter 

 shows its most rapid increase. The dorsoventral diameter continues to 

 increase almost until maturity. The increase in dry matter in the 

 kernel is very uniform throughout the period of growth. The percent- 

 age of water decreases uniformly from flowering to maturity. During 



